Irradiation device and method for the treatment of acne and acne scars

ABSTRACT

An irradiation device ( 1 ) and a method for the treatment of acne and acne scars, comprising at least one source of radiation ( 2 ), the source of radiation emitting at least one broadband spectrum in the wavelength range of 320-at least 540 nm and the radiation source ( 2 ) being pulse-operable and/or movable relatively to the area to be irradiated, the pulse energy being between 0.05-10 J/cm 2  and the peak irradiation intensity being between 0.5 W/cm 2  and 100 kW/cm 2 .

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 10/094,431filed on Mar. 8, 2002, the complete disclosure of which is hereinincorporated by reference, and claims priority to German application no.DE 201 09 899.7.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an irradiation device and a method for thetreatment of acne.

2. Brief Description of the Related Art

It is known to treat acne, which is a skin disease caused byproliferation of bacteria in blocked follicles of areas of the skin thatare rich in sebaceous glands together with keratosis, with blue light inthe range of 400-440 nm without significant proportions of UVA, withlimited success.

Here we refer to the article of V. Sigurdsson et al., “Phototherapy ofAcne Vulgaris with visible Light, Dermatologie 1997, 194; iss. 3,256-260” which includes further literature references. This form oftherapy started by using red fluorescence of acne follicle as part ofthe dermatological examination using a woodlamp. The source determinedfor the flouorescence was the storage of large quantities of porphyrinsin the propionbacterium acne. McGinley et al., Facial follicularporphyrin fluorscence. Correlation with age and density ofpropionibacterium acnes, Br. J. Dermatol. 1980, Vol. 102, Iss. 3,437-441). Since the principal absorption (Soret-band) of porphyrins isaround 420 nm, it was obvious for Meffert et al. to treat acne follicleswith blue light. The longest-wave absorption band of porphyrins is 630nm, with a penetration depth of 4 mm, which is most favorable forphotodynamic follicle treatment and is used for this purpose.

From WO 00/02491 such an irradiation device is known which comprises atleast one narrowband spectrum in the range of 405-440 nm. As alternativeor cumulative areas of the spectrum the wavelength intervals between610-670 and 520-550 nm are given. For further improvement of treatmentefficacy it is proposed to increase the oxygen concentration within theirradiated area by applying oxygen-enriched emulsions before or duringthe irradiation. The irradiation intensity for this is between 10-500mW/cm².

WO 00/64537 describes another irradiaton device for the treatment ofacne. Here the afflicted area is treated with UV light in the range of320-350 nm. The energy input given here is 1-5 J/cm². When using alaser, the pulse energy is supposed to be between 5-25 mJ/cm², so thatpulse lengths of 10 ns will result in an intensity of about 2 MW/cm².The known irradiation device is based on the realization that sunlikespectra are not suitable for acne treatment, but may rather trigger anoutbreak of acne.

From EP 0 565 331 B1 a device for the treatment of vascular diseases inan area of the skin is known, including a housing with an incoherentlight source mounted in that housing and suitable for the emission ofpulsed light for treatment, and an opening in the housing, defining aray of light which is emitted onto the afflicted area of skin withoutpassing through a cable of optical fibres, thus showing a widerirradiation area than devices with optical fibres, the device alsoincluding a low cutoff filter, thus cuffing off the visible and UV partsof the spectrum while the incoherent light source emits a ray of lightcombining wavelengths between 300 and 1000 nm. The light source has anelectrical connection to a pulse-forming-network in order to deliver atime pulse between 1 and 10 ms, the emitted ray of light producing anenergy density between 30 and 100 J/cm², so that the emitted light maypass through a low cutoff filter and penetrate the skin as deeply asdesired without burning of the skin, in order to heat a blood vesselunder the skin in the skin treatment area and to cause blood coagulationin the blood vessel.

The blood coagulation described there is to be avoided in the treatmentof acne, so that the described device is not suitable for the treatmentof acne or other superficial skin diseases.

From DE 93 21 497 U1 a therapeutic treatment device is known, which isoperated with an incoherent light source emitting light pulses, apreferred embodiment using flash lamps which emit light in the range of300-1000 nm. The aim of this method is also the coagulation of bloodvessels. The energy density per pulse is between 30-100 J/cm², so thatwe can refer to our comment concerning EP 0 565 331 B1.

Immunologic examinations of acne patients have shown no abnormalreactions, which leads to the assumption that immunologic processes arenot a factor in the development of primary acne. A secondary factor isf. e. the rupture of the epithelia of the closed comedome that willallow the contents (ceratine cells, hairs, sebum, free fatty acids andbacteria) to come into contact with the connective tissue. This causes aforeign body reaction often accompanied by an acute inflammation of theskin, which is referred to as secondary inflammatory efflorescence.

After the subsiding of the inflammation, there is a third category ofacne efflorescence showing a previous serious outbreak of acne, which iscosmetically disfiguring. These scars have different appearances, suchas small and comedome-like, sunken-in like wormholes or keloid-likeatrophic scars covering large areas.

The known irradiation arrangements for the treatment of acne aretechnically elaborate and therefore costly, especially if a high energydensity in specified areas of the spectrum has to be produced.

Post-inflammatory acne efflorescences cannot be treated with knownirradiation devices without tissue coagulation or ablation. Thereforethe problem of acne scar therapy has not been satisfactorily solved sofar. The excision of crateriform acne scars is invasive and goes with ahigh risk of infection. Facial acne scars can be treated with high-speeddermabrasion devices; keloid acne scars are often treated cryosurgicallywith liquid nitrogen. Both techniques are also elaborate as well ascostly.

SUMMARY OF THE INVENTION

The invention is based on the technical problem of providing anirradiation device and a method for the treatment of acne and acne scarsthat are cost-efficient and show a high treatment efficacy.

Here, the radiation source is designed as a broadband radiation sourcewith wavelengths in the range of at least 320-at least 540 nm which ispulse-operable and/or with the possibility of relative motion to thearea to be treated The pulse energy per pulse is between 0.05-10 J/cm²and peak radiation power of the optical pulses lies between 0.5 W/cm²and 100 kW/cm². At least 320 nm means, that the radiation source canemit shorter wavelengths, but these wavelengths are not transmitted tothe area to be treated but cut off beforehand. Wavelengths longer than540 nm, on the other hand, can be emitted. The invention utilizes thefact that in contradiction to scientific reports pulse operation resp.pulsed irradiation using the same energy as input cw-radiation willinduce an increase in the generation of singlet oxygen of several ordersof magnitude.

It now appears that, surprisingly, that by using pulse operation theaverage radiation power can be pushed below the threshold known fromscientific reports whereas at the same time the efficiency is increased.Contrary to WO 00/64537, the visible parts of the spectrum are alsotreatment efficient, and therefore the invention can draw on inexpensivebroadband radiation sources, making costly lasers or filters expendable.The cause for outbreaks of acne under solar-like radiation sources isassumed to be not in the visible part but in the UVB-part at 320 nm,which the invention does not use. Another advantage over WO 00/02491 isa higher performance, i.e. more energy from the blue part of thespectrum reaching the follicle. Since the hair follicles are situated inthe deeper layers of the skin, only a fraction of the blue part of thespectrum between 400-500 nm reaches the follicles due to very highdermal absorption. Therefore, irradiation devices with a pure bluespectral emission have to use high power and even then the results oftenremain modest. This is only partially due to the low penetration depthof the blue part of the spectrum, but may be more likely related to thepresence of a threshold dose due to antioxidant dermal mechanisms. Thispossibly explains the poor results of Sigurdsson who employed only lowradiation power below or within the range of this threshold.

Unexpectedly, this invention teaches that mean irradiation levels whichare one order of magnitude lower than the threshold of 60 mW/cm²described in WO/022491 and below the irradiation levels employed bySigurdsson and Meffert can be very effective if the peak pulse powerexceeds the described threshold levels for a short time only. Clinicalresults show that the efficacy of a pulsed-light acne therapy comparedto a cw-treatment with an identical spectrum can be increased by afactor of 10-20. The efficacy of acne therapy described in WO 00/02491possibly relates to the killing of superficial bacteria through the bluepart of the spectrum, whereas follicles can only be reached by theaforementioned green and red parts of the spectrum between 520-550 nmresp. 610-670. Pulsed irradiation is much less affected by constantthreshold off-set than cw-irradiation, since the fractional contributionof the off-set is much smaller with pulsed irradiation than withcw-radiation. Therefore, the pulsed blue light which reaches thefollicle can generate singlet oxygen more efficiently.

According to the invention, it is possible to treat not onlyinflammatory acne, but also the post-inflammatory cosmeticallydisfiguring acne scars with good results. Unexpectedly there was adiscoloring of the pigmented scars which flattened simultaneously. Mostlikely, the pigments are bleached by singlet oxygen generated by theblue irradiation In addition, there appears to be a reactive-oxygenspecies-mediated histological remodeling of the skin. Signs ofskin-aging, wrinkles, epidermal and dermal atrophy, coarseness andflabbiness of the skin and increased pore diameter are decreased orreduced. The unexpected skin rejuvenation appears to be related to adermal metabolic change which involves extracellular matrix proteins.There is an increase in procollagen, collagen and collagenase, whichreflects the irradiation-induced remodeling of the skin. The result is apartial or complete reduction of the disfiguring skin changes.

The technical specification of power and energy density always relatesto the irradiated skin surface. The irradiation device will preferablybe put into direct contact with the skin preferably, the effective pulselengths are between 1 μs -500 ms. This relatively broad range stems fromthe different preferred effective pulse lengths for pulsed radiationsources and for relative motion in the form of a scanning device. Thescanner, however, is preferably used for the treatment of skin diseasescovering larger areas.

The preferred effective pulse lengths for flashlamps are between 1 μsand 10 ms and most preferred between 100-600 μs, with th pulse on/offperiods being asymmetric.

This relatively broad range stems from the different preferred effectivepulse lengths for pulsed radiation sources and for relative motion inthe form of a scanning device. The scanner, however, is preferably usedfor the treatment of skin diseases covering larger areas.

The preferred effective pulse lengths for flashlamps are between 1 μsand 50 ms, more preferably between 1 μs and 10 ms and most preferredbetween 100-600 .mu.s, with the pulse on/off periods being asymmetric.

In the scanner embodiment the preferred effective pulse lengths arebetween 1 ms and 500 ms, more preferably between 20-100 ms. Effectivepulse length means the period of time between the achievement of 50% ofmaximum performance and the drop to 50% of maximum performance. Theoff-period between pulses are longer than the effective pulse length inorder to allow the diffusion of depleted oxygen. The ratio of pulseon/off periods is preferably between 3-3000 for the scanner and100-100,000 for the flashlamp. Another effect is the thermal cooling ofthe irradiated area during the pulse-off period, so that necrosis doesnot occur.

In another preferred embodiment the pulse frequency for the radiationsource is between 0.01-100 Hz, more preferably between 0.05-50 Hz andfurther preferably between 0.3-3 Hz, using shorter effective pulselengths and lower pulse energies with higher frequencies.

Just as the effective pulse lengths are dependent on the use of either apulsed radiation source or a source with relative motion, the preferredirradiation intensities resp. peak power densities per pulse are alsodifferent.

In embodiments with a pulsed radiation source the irradiation intensityper pulse is between 1 W/cm²-100 kW/cm², preferably between 50 W/cm²-50kW/cm², more preferably between 500 W/cm²-10 kW/cm² and most preferablybetween 1 kW/cm²-5 kW/cm². The energy density per pulse is between 50mJ/cm²-10 J/cm², preferably between 100 mJ/cm²-1 J/cm² and mostpreferably between 300-1000 mJ/cm².

In embodiments which employ a scanner which in addition may allow forthe pulsing of the radiation source while moving, the power densitiesper pulse are preferably between 500 mW/cm²-5000 W/cm² and between 1-500W/cm² and more preferred between 2-300 W/cm² and even more preferredbetween 3-100 W/cm². The energy density per pulse is between 50 mJ/cm²and 10 J/cm², preferably between 100-3000 mJ/cm² and more preferredbetween 150-100 mJ/cm² and most preferred between 200-500 mJ/cm².

The generation of longer effective pulse lengths is almost impossibleusing the known flashlamps. The generation of these pulse lengths may beuseful to selectively warm the sebum containing follicle and the hairshaft in order to soften the obstructing sebaceous concrements andinduce a reduction of sebum production. Another positive effect may be adecrease in keratinization of epithelial cells in the hair shaft area.These longer pulse lengths may be simulated according to the desiredthermokinetic effects through a precise control of the pulse formingnetwork. For example 100 pulses with an effective pulse lengths of 100μs and a pulse-off time of 900 μs will be generated with no pulsesfollowing for the next 10-1000 ms is will be between 50-300 μs.

In another preferred embodiment the radiation source is a xenonflashlamp. These known xenon flashlamps are inexpensive and emit enoughlight in the preferred spectral range between 320-450 nm resp. 320-670nm. Such flashlamps are mentioned in U.S. Pat. No. 4,167,669 and EP 0565 331, but the described pulse energies are too high for the teachingof this invention. Xenon flashlamps with a medium to high power load canbe spectrally compared to the radiation of a black body. Therefore,xenon flashlamps typically emit between 200-2000 nm. Due the celltoxicity of the wavelength between 200-320 nm, this wavelength band hasto be filtered. Furthermore it is possible to dope the xenon flashlampswith metals or metal halides in order to specifically amplify certainspectral regions. Very suitable therefore are gallium, indium and/ortheir halides.

In another preferred embodiment the radiation source is equipped with adevice for the suppression of the spectral regions between 320-400 nmand/or transformation of this UV-emission into visible radiation. Thistakes account of the fact that all possible cellular adverse effects ofUV radiation can be avoided completely without a reduction of the deviceefficacy. Known inexpensive UVA filters may be used to filter the UVAspectral parts. Preferably, the said UVA parts of the spectrum aretransformed into the visible spectrum by use of suitable inorganicphosphors or organic laser dyes. Well-tried are foils made of siliconeelastomers which have been doped with anorganic phosphors. Due to theprincipal absorption of the porphyrins aroud 420 nm, preferablyblue-emitting phosphors are used and may be combined with green and redphosphors which emit between 520-550 nm and/or 610-670 nm. In analternative embodiment fluorinated polymers such as PTFE may be usedinstead of silicone elastomers. When using inorganic phosphors, for thetransformation of the undesired spectral bands, other radiation sourcessuch as deuterium flashlamps may be used. These flashlamps have a highefficiency in the UV spectral regions which can be transformed intopreferred spectral regions by the aforementioned phosphors.

Another possible irradiation source is an overload-pulsed mercuryiodide-gallium lamp. Overload is defined here as the maximum dischargeenergy being 3-1000 times the nominal lamp current, the pulse dischargeenergy being preferably between 15-1500 A/cm² cross-sectional area ofthe discharge vessel. A description of same standard metal-vapor mercuryhalide lamps can be found f. e. in U.S. Pat. No. 3,521,111; U.S. Pat.No. 3,540,789 and WO 96/13851.

U.S. Pat. No. 5,184,044 shows that with regard to the lamp geometry, thelamp performance of 20 W and the voltage drop of 55 V a lamp current of8/A cm² cross-sectional area of the discharge vessel corresponds to amaximally recommendable lamp load, since there is already an inversionof the indium spectrum. A further increase of current density wouldamplify the inversion up to total deletion.

Those lamps have not been overload-operated so far, since it was knownfrom plasmaphysical studies that narrowband emission spectra can only beproduced when using relatively low excitation energy. Overload operationcauses such an increase of vapor pressure in the discharge plasma thatthe line emission is absorbed by the surrounding plasma and there is aparadox considerable reduction or even complete deletion of theresonance line emission under high discharge pressures. Examples includethe mercury emission at 254 nm, the sodium emission at 488 nm and theindium emission at 450. Here, even moderate overload leads to loss ofspectral intensity in the aforementioned emission lines.

Unexpectedly, it was discovered that galliumiodide-doped mercurymedium-resp. high pressure lamps do show neither broadening nor aninversion of the gallium emission at 403 and 417, even if the overloadis 100-1000 times above normal operating conditions. Agalliumiodide-doped mercury discharge lamp run under normal conditionswith a discharge current of 1.5 A/cm² cross-sectional area of thedischarge vessel could be run in pulse operation mode with 1000 A/cm²cross-sectional area of the discharge vessel without reduction orinversion of the gallium emission lines. A possible explanation relatesto the fact that metallic gallium has a boiling point of 2200° C. sothat the gallium vapor pressure can be neglected even under pulseoperation of the lamp. However, there is a disintegration of mercuryiodide into mercury and iodine. During the plasma discharge, iodineforms an instable compound with gallium, galliumtriiodide. Gal3 shows amarked increase of vapor pressure even at rather low temperatures. Theabsent inversion of the gallium emission could be explained by the factthat Gal3 is only stable up to a certain pressure and there is a rapiddisintegration into gallium and iodine if the pressure is increased anyfurther. Therefore an relatively stable gallium vapor pressure can bemaintained even if there is rapid temperature increase during pulseoperation. After the disintegration of the compound, Gal3 there is acondensation of metallic gallium which does not take part in thedischarge and possible self-absorption of the gallium emission. Thisunexpectedly discovered effect could therefore be related to a paradoxconstant vapor pressure covering a temperature range between 200 andalmost 2200° C. Mercury iodide disintegrates early into mercury andiodine, so that there is always iodine available to form a compound withthe gallium. Mercury pressure therefore may increase rapidly with theenergy load, thus providing excitational energy for the galliumemission. Due to the relatively stable gallium vapor pressure, most ofthis energy is emitted as gallium spectrum lines at 403 and 417 nm.

During overload operation, a temporary overheating occurs, particularlyof the tungsten electrodes, which can emit considerably more heat at arise of temperature, according to Planck's law. Therefore, a modulatedlamp may be operated with an increased base load, since it is due to thetemperature rise that the emission of input energy is considerably moreefficient than in a normal-operated lamp. It so has turned out that a 1kW-lamp can be operated with a steady load of 2-20 kW. Spectralmeasurements have shown the following: When a 1000 W mercury iodidegallium-doped lamp is cw-operated, approx. 400 mW/cm² in the spectralrange of 400-440 nm reach the skin. This irradiation intensity can bedecreased in simmer mode to an average irradiation intensity of 2-4mW/cm², while the irradiation intensity during pulse load is temporarilyincreased by up to four to five orders of magnitude, so that irradiationintensities between 2 and 400 W/cm² reach the skin. The preferred ratioof pulse lengths lies between 3 and 300. This simple pulsed light sourceis also suitable for other technical applications such as f. e. dentalcuring, typographic applications, sealing of surfaces, pipe repair withlight-cured tubing, plastic curing in the DVD production sector as wellas the acceleration of other photochemical reactions that can beinfluenced by radical mechanisms of photoabsorption in the UV-blue rangeof the spectrum.

The ratio of gallium, resp. gallium additive and mercury shouldpreferably be 1:10 to 1:100. In the performance range of 400 W thepreferred ratio of components is 1-5 mg gallium iodide to 44 mg mercury.

Another typical lamp consists of a cylindrical quartz tube with diameter13.5 mm and a discharge vessel with a volume of 20 cm³. The distancebetween the electrodes is 14 cm. This lamp is filled with 20 mg Hg, 3 mgmercury iodide, 1 mg gallium and argon with a pressure of 3.57 mm Hg.

The efficacy of the radiation device can be further increased byenhancement of the oxygen concentration In addition to the measuresdescribed in WO 00/12491 this can be accomplished through oxygeninhalation via an oxygen mask.

Pulse irradiation leads to a perceptible increase in skin temperature,so that preferably a cooling device will be used for the irradiatedarea. This can be a simple air cooling. The cooling device may beassigned to the radiation source. This could be air cooling or otherthermal measures such as a heat sink. Furthermore the fluorescent foilis preferably cooled by air or more preferable by water.

In order to increase the emitted power towards the treatment area, areflector will be added to the radiation source. A preferred type ofreflector is a parabolic reflector with the radiation source beingmounted next to the focus of the parabolic reflector. Other reflectorssuch as hemispheric of similarly formed reflectors can be used.

The irradiated area for a mobile system is in the range of 1-200 cm²,since there is an increase in penetration depth if one uses areairradiation in comparison to point irradiation which is advantageous forthe reaching of the deeper follicles A mobile embodiment allows thesequential irradiation of different acne areas, which are normallylocated in the facial area, the neck area as well as in the area of theupper back and chest.

Alternative embodiments are possible in order to irradiate larger areassimultaneously. A possible embodiment comprises a large number of smallflashlamps, f. e. 30-60 xenon flashlamps which are sewn into a tissue.The tissue may consist of PTFE or PTFE derivatives. High reflectivitycan be achieved through metal vaporization which leads to the desiredair transmission with simultaneous water resistance impact. If amultitude of small radiation sources are used next to the irradiatedobject, it is possible to omit an imaging reflector. With the aid ofsoft, radiation-transparent distance adaptors, f. e. made of siliconeelastomers, cooling of the filters, of the luminescent foils as well asthe irradiated skin areas is achieved with standard air coolers such asCPU coolers.

In another preferred embodiment a device for the generation ofmechanical oscillations is associated with the radiation device.Preferably the mechanical oscillations are time-shifted compared to theoptical pulses. This mode allows the warming and liquefying of thehardened sebum. The following mechanical oscillation then leads to anextraction of the liquefied sebum from the pore.

In a preferred embodiment, this device is an electrodynamic transducer.Opposite flat coils exert push or pull pressures on the skin surface bymeans of a suitable electrical energization. The driving of the coil canuse the current of the radiation device. Alternatively, the device canbe built as a photomechanical transducer where the rapid extension of amaterial by the optical pulse is used to generate mechanicaloscillations.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The invention is explained by describing a preferred example.

FIG. 1 is a cross-section through the irradiation device.

FIG. 2 shows a Spectrum of the radiation source with and withoutluminescent foil.

FIG. 3 is a cross-section through skin with acne follicle.

FIG. 4 is a schematic illustration of an electrodynamical transducer.

FIG. 5 is a schematic illustration of a photoelastic transducer.

FIG. 6 is a schematic illustration effect of cw-operation and pulsedoperation on the relative radiation intensity of a gallium iodid dopedmercury discharge lamp.

FIG. 7 is a graph illustrating the spectral energy density of a galliumiodide-doped mercury lamp at different power loads.

FIG. 8 is a graph relative irradiance of a sodium vapor pressure lamp incw and pulse overload operation.

FIG. 9 is a schematic illustration of a circuit design for pulseoperation of a gallium iodide-doped mercury lamp with two phases of athree phase current.

FIG. 10 is a schematic illustration of an alternative circuit designwith capacitor bank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The irradiation device 1 comprises a broadband irradiation source 2which is preferably a xenon flashlamp. The irradiation source 2 ismounted in the focus of a parabolic reflector 3 which is open on theside averted from the focus. The exit area at the open end of theparabolic reflector 3 is preferably defined through an adjustableshutter. The adjustable shutter can adjust the area to be irradiated.The irradiation source 2 and the paraboloid reflector 3 are mounted in ahousing 5. The housing 5 comprises a handpiece 6 by means of which theirradiation device 1 can be placed on the area to be treated 7. Betweenthe radiation source 2 and the area to be treated 7 there is aluminescent foil 8 arranged which is doped with luminescent particles.The luminescent foil 8 can also be arranged in the proximity of theradiation source 2 or the shutter 4. Preferably, the luminescent foil 8is arranged in a way that makes it easy to replace. This simplifies thenecessary replacement due to aging but also the flexible use ofluminescent foils with different luminescent particles.

Furthermore, an externally mounted luminescent foil 8 can easily bedisinfected. The electrical connectors and the pulse forming network forthe generation of variable pulsewidths are not shown here for reasons ofclarity.

FIG. 2 shows a spectrum of a used xenon flashlamp with and withoutluminescent foil, the spectrum of the luminescent foil is shown as adotted line. The luminescent foil is a silicone elastomere which isdoped with anorganic phosphors which emit preferably in the bluespectral range between 400-450 nm. The luminescent foil cuts off the UVspectral range between 280-400 nm almost totally and transforms said UVrange into the visible blue range between 400-450 nm. The remainingnear-infrared radiation is not shown here.

The xenon flashlamp is timed with a frequency of 0.01-100 Hz preferablybetween 0.1-10 Hz with an effective pulse length of only 10 μs-10 ms.The optical pulse energies lie between 0.5-10 J/cm², preferably between1-3 J/cm². The acne treatment is given over a period of several days orweeks with daily treatment between 1-60 minutes, preferably between 5-10minutes

FIG. 3 shows a cross section of the skin in the proximity of hair. Thehair 9 is connected via narrowed ductus 10 with an inflamed andsebum-congested hair shaft 11 with an enlarged and inflamed sebaceousgland 12. Cw operation with blue light leads to a functional absorptionof the blue light due to low penetration depth (1/e) and due to thedermal threshold for blue light. This is schematically shown by theshort arrow 13. In pulse mode, however, the peak pulse energy is muchhigher than the average energy of the cw-operation so that the constantoff-set due to dermal thresholds is much lower.

Therefore the remaining effective power after off-set substraction isincreased and a larger traction of blue light reaches the deeper areasof the hair shaft 11 resp. the sebaceous gland 12. This light canincrease the local generation of singlet oxygen which is demonstrated bythe longer arrow 14.

FIG. 4 shows the principal scheme of an electrodynamic transducer. Thedevice for the generation of mechanical oscillations comprises a frame15 and a transparent incompressible pistil 16 which is movable withinthe frame 15. The pistil 16 is partially coupled to the skin via anultrasound gel 17. At the margin of the frame 15 resp. pistil 16, flatcoils 18 and 19 are mounted in opposite to each other. The pulsed light20 which is emitted by the radiation source 2 is absorbed by the sebumplug 21 and the sebum 22 below. The sebum plug 21 absorbs light withinthe visible part of the spectrum and in the near infrared, whereas thesebum 22 preferably absorbs within the NIR. This leads to a warming andliquification of the sebum plug 21 resp. the sebum 22. Due to a suitablepolarity between the flat coils 18 and 19 there is an attraction resp.repelling between the flat coils 18 and 19. Since the frame 15 isimmobile the pistil 16 either moves towards or away from the skin whichis shown by the double arrow 23. By these vibrations the liquefied sebumplug 21 is loosened and the sebum plug 21 and the sebum 22 are removedfrom the pore.

FIG. 5 shows an alternative embodiment for the generation of mechanicalvibrations. The device comprises a first layer 24 of an opticallytransparent material with high sound conductive velocity, a second layer25 made of an optically transparent carrier material and a third layer26. On and/or in the second layer 25 light-absorbing dye molecules 27are arranged which can be arranged in stripes or concentric rings. Dueto the absorption of the pulsed light 20 there is a sudden thermalexpansion of the dye molecules 27 which leads to the build-up of apressure wave 28. This pressure wave 28 is non-directional, expandingupwards and downwards. The part of the pressure wave 28 which expandsupwards is reflected by the first layer 24 and again downwards. Thethird layer 26 generates a specific phase-distortion between the lightand pressure wave 28 so that the pressure wave 28 reaches the sebum plug21 only after the plug having been warmed and liquefied. The third layer26 is expendable if near field effects are utilized specifically. Thiscan be accomplished by the generation of local maxima which are closerto the skin surface than λ/2 using frequencies in the kHz range.

FIG. 6 displays a comparison of the relative irradiation power of a 1000W galliumiodide-doped mercury lamp in continuous mode operated at 1000 W(curve a) and in pulsed overload operation (curve b). The average powerin pulse operation mode is 1500 W. It is obvious that even a smalloverload induces a marked rise of the optical emission.

FIG. 7 shows the spectral energy density of a galliumiodide-dopedmercury lamp with a normal operating power of 1000 W if the input poweris changed. Curve a) represents the spectral energy density undercw-operating conditions at 1000 W. Curve b) shows the spectral energydensity at a lowered load of 100 W, and curve c) displays the spectralenergy density with an input power of 10 kW. Low load and overloadoperation were performed in cw-mode. It can be seen that in both casesthe spectral lines of the gallium emission remain stable and there is noinversion of spectral lines. Furthermore, there is an enormousproportional increase of the emission.

In contrast, FIG. 8 shows the different behavior of a sodium vapor lamp.Curve b) shows that pulsed operation with 700 W using a lamp with normaloperation power of 230 W induces a complete inversion of the sodiumspectral emission around 488 nm. For comparison, curve a) shows therelative irradiance at cw-operation under normal power conditions.

FIG. 9 shows a circuit arrangement for the pulsed overload operation ofa galliumiodide-doped mercury lamp. The circuit includes agalliumiodide-doped mercury lamp 30, an ignition device 31, a zerocurrent detector 32, a pulse generator 33, a first relay K1 and a secondrelay K2, a starter switch S1 and a pulse switch 34. Both relays K1 andK2 are connected to a neutral conductor N and the first phase of athree-phase circuit. The galliumiodide-doped mercury lamp 30 isconnected to the second phase V2 of the three-phase-circuit via anauxiliary contact. Via a second auxiliary contact of the starter switchS1 the first phase V1 is connected to the ignition device 31 via thezero current detector 32 via a coil arrangement. The coils L1 and L2 areconnected in series. A third coil L3 is connected in parallel to theaforementioned serial coils and is switched with the contact K2 whichbelongs to the second relay K2. In parallel to the first coil L1 thereis another contact K1.1 which relates to the first relay K1. A secondcontact K1.2 which belongs to the first relay K1 is switched between thesecond relay K2 and the pulse switch 34. The principal function of thiscircuit arrangement is described as follows: By closing the starterswitch S1, the related auxiliary contacts also close. Therefore, thecontact K1 closes and the contact K1.2 opens resp. stays open. The firstphase V1 of the three phase circuit is connected via the closed contactK1.1 through coil L2 with the ignition device 31. In this arrangementcoil L2 functions as an inductive coil limiting the lamp current. Thisswitching condition remains until the galliumiodide-doped mercury lamp30 has reached normal operational conditions. Then the relay K1 openswhich may be a passing make contact. The opening of relay K1 induces theopening of the contact K1.1 and the simultaneous closing of contactK1.2. This activates relay K2 and the coil L1 is switched in series tocoil L2. In this arrangement, coil L2 acts as a simmer coil. Since thepulse switch 34 is still open, the contact K2 also remains open. In thiscondition, the galliumiodide-doped mercury lamp 30 operates in a simmermode. Pulsed operation is started by the pulse generator 33, if the zerocurrent detector 32 detects zero current at the first phase V1 of thethree-phase circuit. Now the pulse switch 34 switches and throughactivation of relay K2, the contact K2 is closed. Now the coil L3 isswitched in a parallel manner, which lowers the total inductivity of thearrangement. Through this, the ignition device 31 receives an overloadpulse. At the end of the pulse, the pulse generator 33 opens the pulseswitch 34. This closes contact K2 and the galliumiodide-doped mercurylamp 30 operates again through the serial arrangement of coils L1 and L2as long as the next pulse is being generated by the pulse generator 33.

FIG. 10 shows an alternative embodiment with a capacitor bank. Allelements which relate to FIG. 9 have been given the same numbers. Incontrast to the embodiment in FIG. 9a TRIAC 35 is arranged between theignition device 31 and the galliumiodide-doped mercury lamp 30. TheTRIAC driver 36 is triggered by the pulse generator 32. The capacitorbank 38 is connected to the electrodes of the galliumiodide-dopedmercury lamp 30 via an IGBT 37 resp. the coil L3. The driver 39 of theIGST 37 is also triggered by the pulse generator 33. The functioning ofthe device is as follows: Again, the starter switch S1 is closed, whichalso closes K1.1 and opens the contact K1.2. The activated TRIAC 35allows the operation of the galliumiodide-doped mercury lamp 30 undernormal load. After that, the relay K1 opens, the contact K1.1. opens andK1.2 closes. The galliumiodide-doped mercury lamp 30 is being operatedin a simmer mode via the serial arrangement of coils L1 and L2 while thepulse generator 33 is activated. In order to allow pulse operation, thezero current detector 32 detects zero current and transmits thisinformation to the pulse generator 33. This generator activates thedrivers 33 and 39 in a way that the TRIAC 35 blocks and the IGBT 37contacts. This switches the capacitor bank to the gailiumiodide-dopedmercury lamp 30 and disconnects the lamp from the supply voltage. At theend of a pulse, the IGBT 37 blocks and TRIAC 35 conducts in a way thatthe galliumiodide-doped mercury lamp 30 is operating in simmer modeagain via coils L1 and L2. It is understood that the coils in theaforementioned technical example relate to general inductivities whichcould be realized differently. For demonstration of the magnitudes theFollowing examples for the coils L1, L2 and L3 are given. L1=500 mH;L2=150 mH and L3=7 mH

The following values for current resp. current density resulting fromthis arrangement are given below. Line 3 gives the values for normalcw-operation as a comparison.

Pulse operation: leff=40 A resp. 11.8 A/cm², I_(peak)=55 A resp. 16.2A/cm²

Simmer mode: leff=1.2 A resp. 0.35 A/cm², I_(peak)=1.7 A resp. 0.5 A/cm²

normal operation leff=5 A resp. 1.5 A/cm², I_(peak)=7 A resp. 2 A/cm²

1. Method for effectuating a dermal metabolic change to skin forfacilitating the restoration of skin from a damaged condition to animproved condition, by means of a pulsable broadband optical radiationsource (2) which emits pulses at pulse energies between 0.05-10 J/cm2 ina wavelength range between 320 nm to at least 540 nm, the peak radiationpower of the optical pulses being between 0.5 W/cm² and 100 kW/cm²,comprising: a) irradiating the area of skin to be restored witheffective pulse lengths between 1 μs -500 ms at pulse frequenciesbetween 0.01-100 Hz for at least 60 minutes.
 2. The method according toclaim 1, further comprising at least one repetition of step a) after 24hours.
 3. The method according to claim 1, wherein the irradiation stepa) is carried out with pulse lenghts and frequencies effective to causean increase in the amount of extracellular matrix proteins to facilitaterestoration of skin from a damaged condition.
 4. The method according toclaim 1, wherein the wavelength of the emitted radiation is higher than400 nm.
 5. The method according to claim 1, further includingadministering topically or inhalatory oxygen before and/or during theirradiation to enhance the oxygen concentration in the area of skin tobe restored.
 6. The method according to claim 1, wherein the radiationsource emits radiation having a wavelength capable of facilitating thegeneration of singlet oxygen to facilitate restoration of skin.
 7. Themethod according to claim 1, wherein the irradiating is carried outusing a radiation source (2) which is a xenon or deuterium flashlamp ora galliumiodide-doped mercury lamp, and includes the step of overloadoperating said radiation source.
 8. The method according to claim 7,further including providing a suppression device and suppressing withsaid suppression device parts of the spectrum in the range between320-400 nm and/or transforming with said suppression device UV parts ofthe spectrum into visible light.
 9. Method for effectuating a dermalmetabolic change to skin for facilitating the restoration of skin from adamaged condition to an improved condition, by means of a pulsablebroadband optical radiation source (2) which emits pulses at pulseenergies between 0.05-10 J/cm² in a wavelength range between 320 nm toat least 540 nm, the peak radiation power of the optical pulses beingbetween 0.5 W/cm² and 100 kW/cm², comprising: a) irradiating the area ofskin to be restored with effective pulse lenghts between 1 μs -500 ms atpulse frequencies between 0.01-100 Hz for at least 60 minutes to causean increase of the amount of extracelluar matrix proteins at orproximate to the area of skin to be restored; and b) at least onerepetition of step a) after 24 hours.
 10. The method according to claim9, wherein the wavelength of the emitted radiation is higher than 400nm.
 11. The method according to claim 9, further comprising the step ofadministering topically or inhalatory oxygen before and/or during theirradiation to enhance the oxygen concentration in the area of skin tobe restored.
 12. Method for effectuating a dermal metabolic change toskin for facilitating the restoration of skin from a damaged conditionto an improved condition, by means of a pulsable broadband opticalradiation source (2) which emits pulses at pulse energies between0.05-10 J/cm² in a wavelength range between 320 nm to at least 540 nm,the peak radiation power of the optical pulses being between 0.5 W/cm²and 100 kW/cm², comprising: a) irradiating the area of skin to berestored with effective pulse lengths between 1 μs -500 ms at pulsefrequencies between 0.01-100 Hz for at least 60 minutes to cause anincrease of the amount of extracelluar matrix proteins at or proximateto the area of skin to be restored; b) at least one repetition of stepa) after 24 hours; c) wherein step a) includes irradiating with emittedradiation having a wavelength higher than 400 nm; d) administeringtopically or inhalatory oxygen before and/or during the irradiation toenhance the oxygen concentration in the area of skin to be restored; e)wherein the radiation source emits radiation having a wavelength capableof facilitating the generation of singlet oxygen to facilitaterestoration of skin; f) wherein the irradiating is carried out using aradiation source (2) which is a xenon or deuterium flashlamp or agalliumiodide-doped mercury lamp, and includes the step of overloadoperating said radiation source; and g) providing a suppression deviceand suppressing with said suppression device parts of the spectrum inthe range between 320-400 nm and/or transforming with said suppressiondevice UV parts of the spectrum into visible light.